麻豆传媒

A small group of whales living in the Gulf of Mexico belong to a new species that has remained undetected for millennia. There are fewer than 100 of them, so they are immediately an endangered species.

The new species belongs to a group called baleen whales, which filter food out of the water and include the largest whale of all, the blue whale. Despite their size, we still haven鈥檛 been able to track down how many species of baleen whale there are.

Scientists recognise a species called Bryde鈥檚 whale (Balaenoptera edeni), which are medium-sized whales that live in and around the tropics. It isn鈥檛 clear if they are all one species, or several, so they are often called Bryde鈥檚-like whales.

There are already thought to be two subspecies, called B. edeni brydei and B. edeni edeni, says Patricia Rosel at the National Oceanic and Atmospheric Administration鈥檚 Southeast Fisheries Science Center in Louisiana. However, since 2003 some Bryde鈥檚-like whales from the Indian Ocean have been recognised as a separate species called Omura鈥檚 whale.

Rosel and her colleagues have long studied Bryde鈥檚-like whales in the Gulf of Mexico. 鈥淲e kind of knew, starting in the 1990s, that there was this resident small population,鈥� she says. In 2014, they published a genetic analysis of tissue samples from the whales, which showed they were genetically distinct from other Bryde鈥檚-like whales. 鈥淏ut we didn鈥檛 have a skull,鈥� which is crucial for identifying a new whale species, she says.

Then in January 2019, an adult male stranded in the Florida Everglades, and the researchers obtained the skull and skeleton. They have now found that the skull is distinct from those of other Bryde鈥檚-like whales. Combined with further genetic evidence, they say this is enough to establish the Gulf of Mexico whales as a new species.

They have named the species Balaenoptera ricei, after whale biologist Dale Rice.

Little is known about their behaviour, says Rosel, although some preliminary readings suggest they may dive deep to feed 鈥� unlike other Bryde鈥檚-like whales, which normally feed near the surface.

But it is clear that they are endangered because surveys suggest there are fewer than 100 of them. Like other whales, they are likely to be threatened by ocean noise, energy exploration and vessel strikes, says Rosel.

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